A prior art valve is disclosed in U.S. Pat. No. 4,431,019; and European Patent Nos. 0,578,168 and 0,085,298.
The valve according to the present invention is particularly intended to be used in a dialysis machine which, in its liquid-preparation stage, comprises a plurality of valves of this type. These valves are usually solenoid-operated. The valve can be of the one-way or two-way type or any multi-way type of valve.
These types of valves are provided with a diaphragm which abuts a valve seat in the valve. Wear arises during operation of the valve and abutment of the diaphragm against the valve seats. The function of the valve deteriorates and after a certain period of time leakage arises. In order to ensure reliable operation of these valves, the diaphragm is thus exchanged once a year. This implies that a service engineer travels out to the machine and disassembles the machine and all of the valves to exchange the diaphragms. The costs for this service are therefore high, and particularly the labor costs.
It has been proposed to arrange the diaphragm in some form of cassette which would be simpler to exchange to thereby reduce the precautionary service time.
One object of the present invention is thus to provide an arrangement in a valve which permits simplified procedures during such precautionary services.
A further object of the present invention is to suggest a construction which implies that the diaphragm does not need to be exchanged, whereby the service costs can be radically reduced.
The present invention thus relates to a valve comprising at least one inlet and at least one outlet for a fluid such as a liquid or gas. The inlet and/or the outlet are provided with a valve seat for cooperation with a diaphragm. An operating arrangement causes the diaphragm to abut the valve seat for selective operation of the valve.